Primary Dendritic Cells Phagocytose<i>Cryptococcus neoformans</i>via Mannose Receptors and Fcγ Receptor II for Presentation to T Lymphocytes

Syme, Rachel; Spurrell, Jason; Amankwah, Ernest K.; Green, Francis H. Y.; Mody, Christopher H.

doi:10.1128/iai.70.11.5972-5981.2002

Cited by 126 publications

(113 citation statements)

References 83 publications

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“…Consistent with this notion, activation of BM-DCs by whole cryptococcal cells was significantly, although not completely, reduced in TLR9 Ϫ/Ϫ mice, and these mice were more susceptible to pulmonary infection with Cn than WT control mice, as shown by the increased live colonies in lungs, when Cap67, an acapsular strain, was used. In this regard, it was recently demonstrated that DCs could incorporate and kill this fungal microorganism (42,43). In our data, the culture supernatants of YC-11, a highly encapsulated Cn, containing much capsular polysaccharides suppressed the production of IL-12p40 by cryptococcal DNA and, in addition, BM-DCs failed to produce IL-12p40 upon stimulation with whole yeast cells of YC-11 in contrast to Cap67 (Fig.…”

Section: Discussionmentioning

confidence: 46%

Deoxynucleic Acids from Cryptococcus neoformans Activate Myeloid Dendritic Cells via a TLR9-Dependent Pathway

Nakamura

Miyazato

Xiao

et al. 2008

The Journal of Immunology

100

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The mechanism of host cell recognition of Cryptococcus neoformans, an opportunistic fungal pathogen in immunocompromised patients, remains poorly understood. In the present study, we asked whether the DNA of this yeast activates mouse bone marrow-derived myeloid dendritic cells (BM-DCs). BM-DCs released IL-12p40 and expressed CD40 upon stimulation with cryptococcal DNA, and the response was abolished by treatment with DNase, but not with RNase. IL-12p40 production and CD40 expression were attenuated by chloroquine, bafilomycin A, and inhibitory oligodeoxynucleotides (ODN) that suppressed the responses caused by CpG-ODN. Activation of BM-DCs by cryptococcal DNA was almost completely abrogated in TLR9 gene-disrupted (TLR9−/−) mice and MyD88−/− mice, similar to that by CpG-ODN. In addition, upon stimulation with whole yeast cells of acapsular C. neoformans, TLR9−/− BM-DCs produced a lower amount of IL-12p40 than those from wild-type mice, and TLR9−/− mice were more susceptible to pulmonary infection with this fungal pathogen than wild-type mice, as shown by increased number of live colonies in lungs. Treatment of cryptococcal DNA with methylase resulted in reduced IL-12p40 synthesis by BM-DCs. Furthermore, using a luciferase reporter assay, cryptococcal DNA activated NF-κB in HEK293 cells transfected with the TLR9 gene. Finally, confocal microscopy showed colocalization of fluorescence-labeled cryptococcal DNA with CpG-ODN and the findings merged in part with the distribution of TLR9 in BM-DCs. Our results demonstrate that cryptococcal DNA causes activation of BM-DCs in a TLR9-dependent manner and suggest that the CpG motif-containing DNA may contribute to the development of inflammatory responses after infection with C. neoformans.

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Section: Discussionmentioning

confidence: 46%

Deoxynucleic Acids from Cryptococcus neoformans Activate Myeloid Dendritic Cells via a TLR9-Dependent Pathway

Nakamura

Miyazato

Xiao

et al. 2008

The Journal of Immunology

100

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“…Several studies have shown that the immune response to fungal pathogens is mediated through MR. Mansour and colleagues demonstrated that blockade of MR with mannan and methyl-␣-D-mannopyranoside resulted in diminished production of IL-2 by a T-cell hybridoma responsive to mannoprotein derived from Cryptococcus neoformans (7). Syme and colleagues demonstrated that blocking MR with an anti-MR antibody resulted in diminished phagocytosis of C. neoformans by human dendritic cells (13). It is not clear from this study whether the addition of mannan or ␣CD206 simply blocked expression of MR on the cell surface through binding or whether it diminished production of MR. Our assumption is that preincubation of cells with mannan and ␣CD206 led to these moieties binding to surface MR, thus making it unavailable to T27K.…”

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confidence: 39%

The Mannose Receptor Mediates the Cellular Immune Response in Human Coccidioidomycosis

Ampel

Nelson

Li³

et al. 2005

Infect Immun

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Mannose is the predominant monosaccharide in the coccidioidal antigen preparation T27K. Mannan and anti-CD206 antibody significantly decreased the surface expression of mannose receptor (MR) on adherent peripheral blood mononuclear cells and reduced the interleukin-2 (IL-2) release induced by T27K. These data suggest that MR mediates IL-2 release by T27K.The mannose receptor (MR) is found on the surface of macrophages and dendritic cells, can bind terminal mannoses found on fungi and other pathogens (6), and has been shown to mediate the in vitro cellular immune response to fungal antigens (7). We used mannan, an MR ligand (11), and anti-CD206 (␣CD206), a monoclonal antibody directed against MR (4), to block the surface expression of MR on adherent peripheral blood mononuclear cells (PBMC) and examined the effect of this on the cellular immune response induced by T27K, a glycosylated coccidioidal antigen preparation (1-3).PBMC, derived from the blood of healthy human donors of known coccidioidal immunity, were resuspended in RPMI 1640 (GIBCO, Grand Island, Mich.) with 10% autologous serum, added to 35-mm flat-bottom wells (Falcon, Becton Dickinson Labware), and incubated at 37°C in 95% air-5% CO 2 . For the first 30 min, mannan (from Sacchyromyces cerevisiae; Sigma Chemical Company, St. Louis, Mo.) or ␣CD206 (from clone 19.2; BD Biosciences Pharmingen, San Diego, Calif.) was added to wells. In some experiments, immunoglobulin G1 (IgG1) (no. 555748; BD Biosciences Pharmingen), the isotype of ␣CD206, was used. Control wells received nothing. After 30 min, 10-g/ml T27K was added to cells and further incubated for 72 h. Adherent cells were removed and incubated with fluorescein isothiocyanate (FITC)-labeled ␣CD206 or FITC-labeled IgG1 for 30 min at 22°C in the dark. Cell viability just prior to flow cytometry was Ͼ90%, as determined by trypan blue exclusion. A gate was set around viable nonlymphocytes and 4,000 events were collected. MR surface expression was measured as the ratio of the geometric mean fluorescent intensity (MFI) of samples stained with FITC-labeled ␣CD206 divided by the geometric MFI of cells stained with labeled isotype. Interleukin-2 (IL-2) and gamma interferon (IFN-␥) concentrations in harvested supernatant were measured using a flow cytometry-based immunoassay (CBA; BD Immunosciences, San Jose, Calif.) or by enzyme-linked immunosorbent assay (R&D Systems, Minneapolis, Minn.).Monosaccharide analysis of T27K was performed by the Glycotechnology Core Resource of the University of California at San Diego by using high-pH anion-exchange chromatography with pulsed amperometric detection after protein denaturization and desalting (A. Datta, personal communication). The Wilcoxon signed-rank test for paired data was employed for statistical analysis. All work was approved by the Human Subjects Protection Program of the University of Arizona.To assess mannan blocking of MR, 3.0 ϫ 10 6 PBMC in 2 ml of RPMI 1640 with 10% autologous serum were incubated for 72 h with or without 3 mg of mannan/ml. Subsequent...

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“…on May 10, 2018 by guest http://iai.asm.org/ masking by the capsule (10,35). Therefore, it is likely that the major role of the MR in defenses against cryptococcosis is recognition of soluble MP released from the fungus.…”

Section: Vol 76 2008 Susceptibility Of Mr Ko Mice To Cryptococcosismentioning

confidence: 99%

Role of the Mannose Receptor in a Murine Model ofCryptococcus neoformansInfection

et al. 2008

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Cryptococcus neoformans is an encapsulated fungal pathogen with a predilection to infect persons with suppressed T-cell function. Cryptococcal mannoproteins (MP) are highly mannosylated antigens which elicit T-cell responses in infected mice and in convalescent patients. Key to the immunogenicity of MP is its capacity to bind to the conserved mannose receptor (MR), CD206, on dendritic cells (DCs). To test the role of the MR in the immune response to C. neoformans, wild-type and MR knockout (MR KO) mice were compared by using in vivo and ex vivo models of cryptococcosis. Following a pulmonary challenge with C. neoformans, MR KO mice died significantly faster than wild-type mice and had higher lung fungal burdens after 4 weeks of infection. Uptake of MP was similar when DCs obtained from wild-type and MR KO mice were compared. Additionally, MP did not upregulate the maturation markers major histocompatibility complex class II, CD86, and CD40 in either wild-type or MR KO DCs. However, MP stimulated lymphoproliferation in CD4 ؉ T cells obtained from the peripheral lymph nodes of infected wild-type but not MR KO mice. These studies demonstrate a nonredundant role for the MR in the development of CD4 ؉ T-cell responses to MP and protection from C. neoformans.Cryptococcus neoformans is an opportunistic fungal pathogen which preferentially afflicts immunocompromised persons, particularly those with AIDS or lymphoid malignancies and recipients of immunosuppressive treatments for solid organ transplants (2). The primary site of infection is generally the lungs. While exposure is thought to be common, most immunocompetent persons are able to contain the infection. However, in the absence of effective CD4 ϩ T-cell responses, the organism can disseminate and eventually cross the blood-brain barrier to produce cryptococcal meningitis (18).The inverse correlation between CD4 ϩ T-cell function and the propensity to develop cryptococcosis has prompted investigators to search for antigens which drive the cell-mediated immune response. In this regard, a family of heavily mannosylated proteins, termed mannoproteins (MP), has been identified as immunodominant antigens in mouse models of cryptococcosis and in patients who have recovered from infection (1,16,26). MP possess serine-and threonine-rich C-terminal regions which serve as sites for extensive O-linked mannosylation. Additional mannosylation may be provided via N linkages (17). These areas of O-linked and N-linked mannosylation promote the recognition of MP by host receptors for mannose, in particular, the mannose receptor (MR, CD206) and dendritic cell (DC)-specific intercellular adhesion molecule 3 grabbing nonintegrin (CD209) (17,21). DCs are the main antigenpresenting cells responsible for the uptake, processing, and presentation of MP to CD4 ϩ T cells (21, 22). Blocking receptors for mannose with mannan or deglycosylating MP results in strongly diminished T-cell responses (21,22,32).The MR is a C-type lectin receptor which recognizes terminally mannosylated molecules (24...

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Primary Dendritic Cells PhagocytoseCryptococcus neoformansvia Mannose Receptors and Fcγ Receptor II for Presentation to T Lymphocytes

Cited by 126 publications

References 83 publications

Deoxynucleic Acids from Cryptococcus neoformans Activate Myeloid Dendritic Cells via a TLR9-Dependent Pathway

Deoxynucleic Acids from Cryptococcus neoformans Activate Myeloid Dendritic Cells via a TLR9-Dependent Pathway

The Mannose Receptor Mediates the Cellular Immune Response in Human Coccidioidomycosis

Role of the Mannose Receptor in a Murine Model ofCryptococcus neoformansInfection

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